Lennox-Gastaut Syndrome

What is Lennox-Gastaut syndrome (LGS)?

Lennox-Gastaut syndrome (LGS) is one of the more severe forms of epilepsy. It usually develops during preschool years and is characterised by several seizure types and developmental delay. Seizures are generally difficult to control due to their resistance to anti-epileptic drugs.

What causes LGS?

Often no specific cause is identifiable, however, some of the known causes include:

  • Developmental malformations of the brain
  • • Genetic brain diseases, such as tuberous sclerosis, and inherited metabolic brain diseases
  • • Brain injury due to problems associated with pregnancy and birth including prematurity, asphyxia (lack of oxygen) and/or low birth weight
  • • Severe brain infections including encephalitis, meningitis, toxoplasmosis and rubella.

In many instances, LGS is a sequel to infantile spasms which are sudden spasms or bending of the body, either at the trunk or neck. These usually commence between three and eight months, and may develop into the mixed seizure pattern,which characterises LGS, at two to three years.

There is also a number of rare childhood diseases which may lead to LGS..

How common is LGS?

It is estimated that LGS occurs in between three to eleven per cent of childhood epilepsies with slightly more males than females affected. The average age of onset is three years.

How is LGS diagnosed?

LGS is diagnosed by some or all of the following:

  • The presence of a mixed seizure pattern
  • Some degree of developmental delay or intellectual disability
  • A typical electroencephalogram (EEG)* pattern of slow spike wave discharges may be present.

*An EEG is a graphic chart which displays electrical activity generated from the brain, recorded at the skin surface of the head.

What are the symptoms of LGS?


Seizures are always of several types and a child may experience some or all of these. The most common seizure types associated with LGS are tonic, atonic and atypical absence seizures. Periods of frequent seizures may be interspersed with periods of relative freedom from seizures. (Refer to the Seizure Types table for more information.)

Intellectual disability

Most children with LGS experience some degree of impaired intellectual functioning or information processing. In approximately 65 per cent of children with LGS, intellectual disability is evident, either previous to or at the time of diagnosis. In other children with LGS, intellectual disability becomes apparent within a year or two of the seizures beginning.

Behavioural disturbances

These include poor social skills and attention seeking behaviour. There are at least four possible causes:

  • The underlying condition causing the epilepsy.
  • The effects of medication
  • The electrical disturbance in the brain in uncontrolled epilepsy
  • Difficulties with interpreting information and understanding the world as others do.

Common seizure types

Seizure name




General stiffening of muscles. No jerking movements. May be limited to a brief increase of muscle tone in the neck and arms. Stiffening of the trunk and legs can lead to sudden falls. Commonly occur during sleep.

Several seconds to a minute


Sudden loss of muscle tone causing limpness and collapse to the ground. May result in injury. May involve head nodding or sagging at the knees.

One to four seconds

Atypical absence

Brief period of immobility with a stare. Responsiveness decreased but may not be completely abolished. Different EEG pattern from typical absence seizures. Onset less abrupt and recovery more gradual than typical absences.

Five to thirty seconds

How is LGS managed?

Medication Anti-epileptic drugs (AEDs) are usually the best treatment for seizures although complete seizure control is rarely achieved. LGS often requires frequent changes in dose and type of medication, with some medications losing their initial effectiveness. Unlike most childhood epilepsies, the simultaneous use of more than one type of medication is often necessary.

The AEDs most commonly prescribed for LGS are listed in the table below. There are also a number of new AEDs currently being trialled in Australia and overseas, which appear to be achieving good results with LGS. This includes Lamotrigine.

Common AEDs prescribed for LGS

Trade name

Generic name

Side effects


Sodium valproate

diarrhoea; abdominal pain; nausea; vomiting; weight gain.

Lamictal Lamotrigine rash, interaction with valproate causing nausea, vomiting, anorexia; interaction with Tegretol (Carbamazepine) causing double vision, unsteadiness.



aggression; depression; drowsiness; sedation; ataxia (poor coordination); drooling.



drowsiness; weight gain.



behavioural disturbances; nausea, drowsiness; decreased appetite; abdominal pain; unsteadiness; hiccups; headaches; rashes.

Topomax Topirimate weight loss, sedation, word finding difficulties, tingling, kidney stones

(Refer to the Epilepsy Medications brochure in this series for more information about commonly prescribed AEDs and possible side effects.)


A ketogenic diet is a special diet which has been clinically effective in reducing seizures. This type of diet was commonly used before the availability of modern anti-epileptic drugs but is rarely used today. It is very high in fat, often unpalatable and requires strict compliance.

In addition, the ketogenic diet elevates blood cholesterol levels markedly and is expensive to implement. It is not a long term proposition.

Vagus nerve stimulation

The vagus nerve stimulator is a device, similar in size to a heart pacemaker, which is implanted in the chest with a lead that passes up to the neck and is placed around the vagus nerve. This device stimulates the vagus nerve for about 30 seconds every 5 minutes and has been shown to improve seizure control in people with uncontrolled seizures. The device may take up to a year to show maximum benefit. This device requires an operation for insertion as well as for removal. The batteries require replacement approximately every 5 years which would entail further surgery.

Attention to seizure triggers

It is recognised that the frequency of seizures may be associated with the child's level of alertness. The child who is overexcited for example or lacks sufficient stimulation, may experience more seizures.

Therefore, a stimulating but stable environment can be important in reducing the number of daily seizures. This may include a strict routine of regular meals, sleep and medication.

Illness may also trigger seizures. For example, often seizure activity may increase just before the onset of high body temperature and fever. Vomiting and diarrhoea can also affect the body's ability to absorb medication.

Status epilepticus

Status epilepticus (status) occurs in about 50 per cent of people with LGS. It is the term used to describe prolonged seizures of 30 minutes or more or the occurrence of repeated seizures without regaining consciousness between attacks.

Status can occur with any type of seizure and is categorised as either convulsive or non-convulsive. Status can last from hours to days or in the case of non-convulsive status, even weeks or months. Factors which may lead to status include sudden withdrawal from medication, illness, fever and infections.

Status in children with LGS is most often non-convulsive. It is characterised by severe confusion, apathy or a `flat' mood, stupor or at worst, apparent dementia. Inconspicuous muscle spasms and greatly impaired balance and coordination are usually evident.

Convulsive status may ultimately lead to brain damage and death unless stopped quickly. Usually it is stopped by administrating rectal valium. Some parents and carers learn to administer rectal valium at home. This option would need to be discussed with your doctor.

What does the future hold for a child with LGS (prognosis)?

One parent comments: "Basically, I wanted to know what she would be like as an adult - that is how far I was looking forward as time goes on, your concerns come back a bit closer to the day-to-day"

To date, little research has been conducted into the prognosis of children with LGS. It is clear, however, that prognosis varies from child to child.

Generally, this syndrome is permanent. A few years after diagnosis, the epilepsy which was initially so difficult to control, may become less of an issue but impaired intellectual functioning and behavioural problems frequently persist. Complete recovery with freedom from seizures and normal development, is very unusual for the child with LGS.

Practical suggestions

(to help carers support the child with LGS)

  • Consider using respite care schemes which are provided by local councils and other organisations. These schemes offer the opportunity to have a professional carer visit your home to look after the child or place the child with another family or residential centre, either on a regular or occasional basis.
  • Keep a diary which details the child's seizures, seizure precipitants and any side-effects of current medications. This can be useful when reporting to doctors and in identifying seizure patterns and medication responses.
  • Use an intercom in the child's bedroom to monitor any changes in their condition.
  • On outings, consider using a child-stroller for school age children going through a phase of frequent seizures.
  • Question your doctor about all aspects of the child's treatment, including medications and their side effects to ensure that you are sufficiently informed to confidently coordinate the day-to-day management of the condition.
  • If you have any unanswered questions about medications, contact your local pharmacist. Do not alter your child's medication schedule without consulting your doctor.
  • Consider using a hand-held harness to help prevent falls and a helmet to protect the face and head.
  • Lower the temperature on the household's hot water unit or install a low temperature hot water service to prevent scalds and burns.
  • Buy a dosette box and tablet cutter from your local pharmacy to assist in preparing and administering medication. The Independent Living Centre (Tel: 03 9690 9177) offers information and a range of aids which may assist in supporting the child with LGS.
  • The Independent Living Centre (03) 9362 6111 offers information and a range of aids which may assist in supporting the child with LGS.

Coping with LGS

In the words of parents themselves

  • "You can worry yourself to death about all sorts of things really. I don't think about the future, I think about today. That's the way I cope with it."
  • "Sometimes I cope and sometimes I don't. In a way, you cope because you have to. Some days it's a more positive coping than other days."
  • "I'm a bit of a fatalist. I just accept things. It's happened and you have to cope with it. You just roll along then all of a sudden it hits you - you'll have a cry or something will just happen but, once you get it off your chest, you just roll along again."
  • "You start to make limits on how far into your life it's going to intrude and how much you are going to let it affect you outside the home."

Uncontrolled Epilepsy Parents' Support Group

The Epilepsy Foundation of Victoria Incorporated coordinates a support group for parents and carers of children with LGS and other forms of uncontrolled epilepsy.

Daytime and evening meetings are held in Camberwell and often include professional speakers.

Those who are unable to attend meetings can be included on the mailing list which is comprised of some 100 families from around Australia and other countries across the world.

For more information, contact the Epilepsy Foundation of Victoria (03) 9813 2866 Fax (03) 9882 7159 Toll-free 1300 852 853

Published by the EFV Medical consultant: Dr Ian Hopkins (courtesy Royal Childrens Hospital, Melbourne)

EMAIL epilepsy@epilepsy.asn.au    818 Burke Rd, Camberwell Victoria  3124  Australia
PHONE (03) 9805 9111    TOLL FREE 1300 852 853    FAX (03) 9882 7159